Liquid fluorine-containing polymer and its production with iodinated compound

A process for producing a readily crosslinkable liquid fluorine-containing polymer having a number average molecular weight of 900 to 10,000 and containing iodine in the molecule in an amount of 1 to 30% by weight based on the weight of the polymer, which comprises polymerizing vinylidene fluoride and at least one other fluoroolefin in the presence of a radical-producing source and an iodinated compound of the formula RfI.sub.x, wherein Rf is selected from at least one member of the group consisting of a saturated perfluorocarbon group, a saturated perfluorochlorocarbon group or a saturated fluorochlorohydrocarbon group and x is an integer of not less than 1 corresponding to the bonding valency of Rf while maintaining the proportion of the mole number of the monomeric components (M) to the mole number of the iodinated compound (I) in a range between 10 and 1,200.